The criminal section of the Supreme Court upheld a conviction against the country's former statistics chief to two years in prison for breach of duty, dismissing an appeal to revert the sentence.
A lower court had handed down a suspended sentence to Andreas Georgiou in August 2017, finding him guilty of not getting approval by the then board of ELSTAT before transmitting the 2009 deficit figures to Eurostat.
The case of Georgiou has attracted intense criticism from Greece's international lenders who fully support his efforts between 2010 and 2015 to provide credible statistics on the country's finances.
Eurostat, the European Union's official statistics service, has issued a series of statements over the years defending Georgiou and his figures.
Georgiou will also face for the third time charges over accusations he falsified budget data to justify Greece's first international bailout. He has already been cleared twice in judgments by the Council of Appeals Court Judges.
Criminal charges of making a false statement were first brought against Georgiou in 2013 after members of the then existing board for ELSTAT accused Georgiou and other ELSTAT statisticians of artificially inflating Greek budget figures in 2009.